John hall and heney hall



UNITED STATES JOHN vHALL AND HENRY HALL, sa.,

PATENT OFFICE.

OF PHILADELPHIA, PENNSYLVANIA,

iMPRovEr/IENT iN PlsToNs Foa STEAM-ENGINES.

Specification forming part of Letters Patent No. 4 l,96l, dated March l5, 1864.

To @ZZ whom it may concern,.-

Beit known that we,Jo.HN HALL and HENRY HALL, Sr., both of Philadelphia, Pennsylvania, have invented an Improvement in Pistons; and we do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, and to the letters of reference marked thereon.

Ourinvention consists of a piston constructed in the peculiar man ner fully described hereinafter, with the View of readily expanding the packingrings equally at all points from the exterior of the piston.

In order to enable others to make and use our invention, we will now proceed to describe the manner of constructing and operating the same.

On reference to the accompanying drawings, which form a part of this specication, Figure l is a plan View of our improved piston with the upper plate removed; Fig. 2, a vertical section on the line l 2, Fig. l; Fig. 3, a vertical section on the line 3 4t, Fig. 1, and Fig. 4- an inverted plan view of part of the piston.

Similar letters referto similar parts throughout the several views.

A is the central hub of the piston, into the opening a of which the piston-.rod is iitted and secured, the tlange or plate b forming part of the hub,to the upper portion of which is fitted the annular plate B. Between this plate and the ilange b are the upper and lower rings, D and D', each of which is severed at one point, so that it can be expanded when necessary. Within these rings are arranged the three segments E, E', and E", of equal dimensions, these segments iitting snugly to the interior of the rings D and D', as seen in Fig. 2.

Three ribs, F, F', and F", radiate from the hub A of the piston and extend to within a short distance from the inside of the segments. An inclined surface, f, is formed on each rib, against which surface bears one of the inclined sides of the triangular wedge G, the other inclined side of which bears against the beveled end of a block, H, one of which is arranged to fit snugly, but to slide to and fro freely,between one of the ribs, F, and a projection, I, which forms a part of the flange b of the piston.

f An annular plate, K, is fitted snugly but so as to turn freely on the hub A of the pistonl` and occupies a position immediately below the plate B. On the under side of this annular plate K are three projections, m m m, the

' rounded edge of each of which is arranged'to bea-r againstl one of the wedges G, as best observed on reference to Fig. l.

rlwo lugs, a and n', project from the annular plate K, and theselugs carry the spindle q, on one of which are cut screw-threads adapted to internal threads in the lug n, the other end of the spindle being plain and arranged to turn and slide freely in the projection n.

On the spindle q is a wheel, M, having teeth adapted to a worm, N, formed on the vert-ical spindle P, the lower end of which turns in a socket formed in the iiange b of the piston, the upper end projecting through and having its bearing in the plate B, and the spindle being maintained in its proper position by a collar, t, adapted to a recess t'ormedin the under side of the said plate B, as seen in Fig. 2. The screwed end of the spindle q bears against a steel spring, B, secured to the hub of the spindle. (See Fig. l.)

When the above-described parts are itted to their proper places, and it becomes desirable to expand the rings D and D', thereby increasing the diameter of the piston, a suitable Wrench or screw-key is applied to that portion of the vertical spindle Pwhich projects above the plate B. On turning this spindle the partial turning of the spindle q must take place, and as the screwed end of this spindle acts on the spring B, it necessarily follows that the annular plate K must be turned on the hub of the piston to a limited extent, and that each projection m must push one of the wedges G against the inclined surface of one of the ribs and against the beveled end of one of the blocks H. The three blocks are consequently forced ont simultaneously against the segments, and these being forced against the rings D and D', the latter must necessarily be expanded and the diameter of the piston increased.

By using a spring, B, for the spindle q to bear against, a limited elasticity is imparted to the rings D and D', so that there is a constant tendency of these rings to bear against the interior ot' the cylinder, even after they have become slightly worn, which ,would not be the case if a rigid project-ion were substituted for the spring R. In ordinary pistons a number of springs are used for forcing out the rings;

and as different springs must of necessity `diii'er more or less in quality, elasticity, and temper, it follows that the rings must be eX- panded unequally. In our improved piston the case is diii'erent,as but one spring is used, and the action of this Vspring tends to force out all thesegments and rings equally.

It will be observed that each sliding block H is situated at the point where two ot' the segments meet or approach each other, one portion of the block bearing against onesegment and the other against the other segment. There are two advantagesin this arrangement: First, it is importantin forcing out the segments that their form should not be changed by the force applied, which would be the case it' they were acted on near the middle of each segment. By applying the force at the oppositeends of each segment this difculty is obviated, as each segment forms an arch the form of which it is most difficult to change by any force applied to the ends.

The second advantage of the peculiar arrangement of the sliding blocks is that each block covers the space between two adjacent segments, and forms an efficient joint for preventing the steam from gaining access to the interior of the piston.

` Although we have illustrated and described our improved piston as furnished with but three radial ribs, F, F', and F, three blocks, H, and three wedges, G, it will be evident that the number of these parts may be increased according to the dimensions of the pistons.

We prefer the use of the Worm-wheel and screwed spindle as mediums for turning the structed and arranged for action on `the segments and rings of the piston, substantially as and for thepurpose herein. set forth.

2. The arrangement within described ofthe sliding blocks H in respect to the segments, for the purpose speciiied.

3. The Worm-spindle P, and the screwed spinf die ),with its wheel M, when the whole is combined with the annular plate K, and arranged for operating the same, substantially as de scribed, for the purpose specified.l p

4. The use ofthe single spring Riferimparting an equal pressure and elasticity `to the rings, substantially in the manner de-` scribed.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

JOHN HALL. HENRY HALL, SR.

Witnesses: HENRY HoyvsoN,

JOHN WHITE. 

